Finding the Fourth Proportional to 100.81, 138.72 and 76.18

Step by Step Solution

1. Step 1: Write the proportion equation
   100.81 : 138.72 = 76.18 : x
2. Step 2: Convert to fraction form
   100.81/138.72 = 76.18/x
3. Step 3: Cross multiply
   100.81x = 138.72 × 76.18
4. Step 4: Simplify right side
   100.81x = 10,567.69
5. Step 5: Solve for x
   x = 10,567.69/100.81
6. Step 6: Final answer
   x = 104.83